HH\Traversable

Represents an entity that can be iterated over using foreach, without requiring a key

The iteration variable will have a type of T.

In addition to Hack collections, PHP arrays and anything that implement Iterator are Traversable.

In general, if you are implementing your own Hack class, you will want to implement Iterable instead of Traversable since Traversable is more of a bridge for PHP arrays to work well with Hack collections.

Guides

• Introduction
• Interfaces

Interface Synopsis

namespace HH;

interface Traversable {...}